ByTaylor Barnes, CorrespondentNovember 2, 2010

Police stand outside the Greek Parliament after a controlled blast in Athens on Nov. 2. Greek police say they have detonated another suspicious package outside the Bulgarian Embassy in Athens, following blasts outside Parliament and the Swiss Embassy.

So-called "parcel bombs" exploded today in the compounds of the Swiss and Russian embassies in Athens, injuring no one, according to the Associated Press. They came a day after another parcel bomb, which was addressed to the Mexican Embassy in Greece, exploded in the offices of an Athens courier company.

The explosion Monday injured one female worker and led police to two suspected culprits standing at a bus stop near the building. Aged 22 and 24, the men were arrested holding two more parcel bombs addressed to French President Nicolas Sarkozy and the Belgian Embassy in the Greek capital, reported The Canada Press.

A sixth parcel bomb addressed to the Dutch Embassy was discovered Monday by police at the offices of ACS couriers, also in the neighborhood of Pagrati. And yet a seventh and eighth parcel bomb, addressed to the Bulgarian Embassy and Chilean Embassy respectively, were detonated today in controlled explosions, reported BBC News.

Coming days after authorities in Britain and Dubai intercepted several bomb packages mailed out of Yemen and addressed to Chicago synagogues, the citywide terror plot puts a spotlight on how radical groups can utilize a global mailing system criticized for lax screening.

The younger man is alleged to belong to a domestic anarchist group referred to as "Conspiracy Nuclei of Fire" (the media also refers to it as "Conspiracy of Cells of Fire" or "Conspiracy of Fire"). Their motivation is reportedly to spark a revolution in Greece. The group is alleged to be behind a wave of attacks since December 2008, according to the Canadian Press.

But police, the post office, and private delivery companies say screening procedures have not changed significantly since a senior official at the country's public order ministry was killed last year in a letter-bomb blast linked to Greek militants.

Parcels sent by private courier are sealed in front of a company employee and the sender, and they are only X-rayed if they pass through an airport.

Bloomberg reported that the suspects were identified as Greek nationals and found with two pistols and ammunition. One was carrying a wig and bulletproof vest. A man wearing a similar disguise had been reported at the courier firm the week beforehand, inquiring about procedures for sending packages. His disguise was memorable to the female employee, according to the Athens News Agency.

While The Canada Press reported that the initial bomb Monday "went off in the hands of a female delivery-service employee," the BBC reported "the first package detonated when a woman working at the courier company became suspicious of the contents and threw it to the ground."

Though this incident is linked to domestic groups, Europe and the United States have been on heightened alert over international freight security since last week’s announcement that package bombs found on planes in Britain and Dubai were bound for Chicago synagogues.

Germany and Britain today restricted freight on flights from Yemen, as those packages seemed to be from the Yemeni Al Qaeda in the Arabian Peninsula. A Yemeni official criticized their measures as “exaggerated” and unproductive for the country’s own antiterrorism efforts, Blomberg reported.

"One of the things this definitely shows is the need for more and more robust intelligence both here and overseas," Dr. Henry says. "No system is going to be 100 percent effective – that's why we have to have a layered defense – because something will always slip through one layer or the other."